Main points:

The attacker and defender must use a common rhythm as this in a training exercise not real sparring. The idea is not to try and catch out your partner but to practice together.

The distance between A and b can be flexible according to the technique to be used, though one full step length is normal. However the attacker should adjust the distance either closer or further depending on the technique the plan on performing.

1-step sparring is close to a real self-defence situation. Students should use all the offensive and defence techniques they have learned from 4-directional punch to their current pattern including and techniques they have learned in their fundamental movements in class. Jumping techniques should also be performed.

Counter attacks to the vital point and soft target e.g. back, neck, kidneys, knees, eyes, throat should be encouraged but execute with great care (with no contact).

A should attack with a right sided technique first (either foot or hand) and then returns to parallel ready stance. A then attacks with a left sided technique (not the same technique as the right side), then returns to parallel ready stance.
Then B attacks with the right side and then the left side as above. The purpose of this is to practice with both right and left sided techniques.